CA1317370C - Method and apparatus using multiple codes to increase storage capacity - Google Patents
Method and apparatus using multiple codes to increase storage capacityInfo
- Publication number
- CA1317370C CA1317370C CA000577641A CA577641A CA1317370C CA 1317370 C CA1317370 C CA 1317370C CA 000577641 A CA000577641 A CA 000577641A CA 577641 A CA577641 A CA 577641A CA 1317370 C CA1317370 C CA 1317370C
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- 238000000034 method Methods 0.000 title claims abstract description 14
- 238000000638 solvent extraction Methods 0.000 claims description 5
- 230000003213 activating effect Effects 0.000 claims 1
- 230000007704 transition Effects 0.000 description 15
- 238000013459 approach Methods 0.000 description 4
- 230000005415 magnetization Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007476 Maximum Likelihood Methods 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/012—Recording on, or reproducing or erasing from, magnetic disks
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
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- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
- Digital Magnetic Recording (AREA)
Abstract
ABSTRACT OF THE INVENTION
METHOD AND APPARATUS USING MULTIPLE CODES TO
INCREASE STORAGE CAPACITY
To increase storage capacity of a disk storage device, the recording surface of the device is partitioned into a plurality of concentric recording bands, data to be recorded on respective bands are encoded using different run-length-limited codes with the code rate of each band being higher than the adjacent inner band.
METHOD AND APPARATUS USING MULTIPLE CODES TO
INCREASE STORAGE CAPACITY
To increase storage capacity of a disk storage device, the recording surface of the device is partitioned into a plurality of concentric recording bands, data to be recorded on respective bands are encoded using different run-length-limited codes with the code rate of each band being higher than the adjacent inner band.
Description
s 1317~7~
MET~OD AND APPARATUS USING MULTD~LE CODES TO
INCREASE STORAGE CAPACITY
TECHNICAL FIELD
This invention relates to disk storage devices. More particularly, it relates to method and apparatus for increasing data storage capacity of disk storage devices.
BACKGROUND OF THE INVENTION
In magnetic disk recording, it is well known that customer information data bits are recorded as transitions of magnetization along a disk track. If the dsta bit is a "1", then a magnetization transition is recorded (say, from north to south). If the next data bit is also a "1", another magnetization transition is again recorded (this time from south to north). On the other hand, if the data bit is a "0", then no tranæition is recorded. Crowding of transitions causes intersymbol interferences (ISI) and makes data recovery more difficult due to resolution limitation in the readback head. As the maximum data density of a storage device is limited by the amount of intersymbol interferences that can be tolerated by its read/write channel, the traditional approaches to increase storage cspacity of disk storage devices have been directed to overcoming the ISI limitation. One of these approaches is partial response maximum likelihood (PR~L) detection, which seek to improve the detection capability of recorded signals in the presence of noise.
. , . . . ., ,. . ~.. ....
~317370 Another way to alleviate crowding is to use a code that requires n "O's" between consecutive "l's" to thereby reduce transition crowding by a factor of n+l, and codes that have this property are called run-length-limited (RLL) codes. Examples of such codes are the (2,7) code, which requires two "O's" between consecutive "l's" and the (1,7) code which requires one "0" between consecutive "l's".
RLL codes alleviate transition crowding by introducing redundant "O's" to prevent the occurrence of consecutive "l's". Hence, the number of encoded bits is greater than the number of customer bits, the difference being the number of redundant bits. However, while RLL codes introduce redundant bits into a string of customer information bits, they increase the overall effective storage capacity of a recording device by allowing, as the result of such introduction, transitions to be recorded further apart. The rate of a code is defined as the ratio of the number of customer bits to the number of encoded bits. The (2,7) code has a rate of 1./2 and the (1,7) code has a rate of 2/3. Magnetic recording systems today use one code throughout the disk recording surface, and also record the same number of bits on each track. However, because the inner tracks are shorter, the transitions are more crowded on the inner tracks than on the outer tracks .
The industry is seeking to incresse data capacity by making the density of transitions more uniform throughout the disk surface.
"Constant density recording comes alive with new chips", Electronic Design, November 13, 1986, p. 141, is evidence of the approach currently being taken. The articLe suggests using a higher clock frequency for outer tracks, hence increasing the number of transitions ~ 31737~
recorded there and the overall disk surface capacity. Because of the higher clock frequency used on outer tracks, more bits are recorded as the disk rotates one revolution.
Varying the frequency in this manner presents some engineering problems in designing the channel to handle a range of frequencies.
Also, synchronous DASD architectures are less amenable to variable bit rates than nonsynchronous architectures. Other attempts include the suggestion of making outer tracks narrower than inner tracks; or ~Tarying the rotational speed of a disk faster as a function of increasing track radii, so that a constant rate of transition can be recorded throughout the disk surface. To those skilled in the art, however, it i6 readily clear that these approaches are inefficient because of the complicated mechanical design and implementation involved.
.
An object of this ilivention is to increase disk storage capacity by exploiting track length differènces between outer tracks and inner tracks. It is another object of this invention that such increase be accomplished with only minimal impact on the design, such as using only a single clock frequency, and manufacturing of the disk device.
This invention accomplishes uniformity of transition density throughout a disk surface by keeping the same clock frequency, but changing the code used. Outer tracks use higher rate codes than inner tracks. That is, the code used on outer tracks requires fewer "0's" between "1's". The use of higher rate codes on the outer tracks tends to equalize the transition densities between the outer and inner tracks. And, because higher rate codes encode more customer bits per transition, the outer tracks contain more customer information than the , . . ~, . . . . .
l3~7~7a inner tracks. The result is an increase in disk surface capacity and a more uniform transition density throughout the surface.
According to this invention, the method in which the above objects are satisfied comprises the steps of: partitioning recording tracks of the device into a plurality of recording bands, including a first band surrounded by an outer band; encoding data being recorded on said first band under a first run-length-limited code; and encoding data being recorded on said outer band under a second run-length-limited code having a higher code rate than said first run-length-limited code.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram of the disk subsystem which embodies the present invention; and Fig. 2 illustrates a disk-` surface partitioned into recording bands according to this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig. 1 illustrates a general implementation of the present invention. In the block diagram of Fig. 1, there is shown a disk storage subsystem which comprises a disk controller 1 for receiving and executing disk read/write commands from a processing unit (not shown), write driver 2 for writing data into the disk stack 3, and detector 4 for reading stored data from the disk stack 3. Details concern;ng the operation of controller 1, the write driver 2 and the ~ 317~7~
detector 4 are all well known in the art and therefore need not be described here.
Included in the disk storage subsystem is a plurality of RLL
encoders 7a,7b, . . ,7n along with their respective counterpart RLL
decoders 9a,9b,.. ,9n. Each encoder has a different code rate, which is commonly understood as the ratio between the number of input data bits to the number of encoded bits produced therefrom (for example, the code rate is 1:2 for the (2,7) code, 2:3 for the (1,7) code, and 8:9 for the (0, 3) code) .
By way of example, the operation of a disk storage subsystem having a (1,7) RLL encoder and a (2,7) RLL encoder is now described.
An example of a (1,7) RLL encoder can be found in U.S. Patent No.
3,689,899 and an example of a (2,7) RLL encoder can be found in U.S.
Patent No. 4,413,251).
As illustrated in Fig. 2, the recording surface of each disk is divided into an inner recording band Bi extending from the track with radius R1 to a track with radius R2, and an outer recording band Bo extending from the track with radius R2 to the track with radius R3.
Data to be recorded on Bi will be encoded under the (2,7) code while data to be recorded on Bo will be encoded under the (1,7) code.
Although the recording surface can be divided in many different ways, it is obvious that the division should be made to maximize the storage capacity of the surface given the set of RLL codes.
Included in each disk read/write command is a track address, from which the controller 1 generates a head position signal S for directing, 131~
via the head servo control 6, the recording/sensing head of the disk stack 3 to a radial position where the corresponding operation of the disk command is to be performed.
In performing a write operation, the data to be stored is received by both the (1,7) and the (2,7) encoders. However, only the output of one encoder is selected by encoder select 8 to be gated to write driver 2 for wrîting into the disk stack 3. This selection is made by comparing the corresponding head position 5 of the operation with the values R1, R2 and R3. As a result, data stored in inner band Bi will be encoded under the (2,7) RLL code while data stored in outer band Bo will be encoded under the (1,7) RLL code, which has a higher code rate than the ( 2,7) code .
Similarly, in performing a read operation, the signal from the detector 4 is received by the (i,7) decoder and the (2,7) decoder.
However, only the output of one of these decoders is selected by decoder select 10 to be gated` to controller 1. The selection is also based upon comparison between the corresponding head position with R1, R2 and R3-It will be understood that if desired, the recording disk may be partitioned into more than two concentric recording bands, with each respective band having a higher run-length-limited code rate than any corresponding adjacent inner band. For example, the recording surface can be partitioned into an innermost first band wherein data is encoded under a (2,7) RLL code, a second band, on the outside of the first band, wherein data is encoded under a (1,7) RLL code, and an outermost is third wherein data is encoded under a (0,3) RLL code.
~317~l~
Also, if desired, other RLL codes, or other combinations of R~L codes may be used. While the codes can be varied, the same clock frequency is always maintained in any given embodiment.
While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in detail may be made therein without departing from the spirit, scope and teaching of the invention.
MET~OD AND APPARATUS USING MULTD~LE CODES TO
INCREASE STORAGE CAPACITY
TECHNICAL FIELD
This invention relates to disk storage devices. More particularly, it relates to method and apparatus for increasing data storage capacity of disk storage devices.
BACKGROUND OF THE INVENTION
In magnetic disk recording, it is well known that customer information data bits are recorded as transitions of magnetization along a disk track. If the dsta bit is a "1", then a magnetization transition is recorded (say, from north to south). If the next data bit is also a "1", another magnetization transition is again recorded (this time from south to north). On the other hand, if the data bit is a "0", then no tranæition is recorded. Crowding of transitions causes intersymbol interferences (ISI) and makes data recovery more difficult due to resolution limitation in the readback head. As the maximum data density of a storage device is limited by the amount of intersymbol interferences that can be tolerated by its read/write channel, the traditional approaches to increase storage cspacity of disk storage devices have been directed to overcoming the ISI limitation. One of these approaches is partial response maximum likelihood (PR~L) detection, which seek to improve the detection capability of recorded signals in the presence of noise.
. , . . . ., ,. . ~.. ....
~317370 Another way to alleviate crowding is to use a code that requires n "O's" between consecutive "l's" to thereby reduce transition crowding by a factor of n+l, and codes that have this property are called run-length-limited (RLL) codes. Examples of such codes are the (2,7) code, which requires two "O's" between consecutive "l's" and the (1,7) code which requires one "0" between consecutive "l's".
RLL codes alleviate transition crowding by introducing redundant "O's" to prevent the occurrence of consecutive "l's". Hence, the number of encoded bits is greater than the number of customer bits, the difference being the number of redundant bits. However, while RLL codes introduce redundant bits into a string of customer information bits, they increase the overall effective storage capacity of a recording device by allowing, as the result of such introduction, transitions to be recorded further apart. The rate of a code is defined as the ratio of the number of customer bits to the number of encoded bits. The (2,7) code has a rate of 1./2 and the (1,7) code has a rate of 2/3. Magnetic recording systems today use one code throughout the disk recording surface, and also record the same number of bits on each track. However, because the inner tracks are shorter, the transitions are more crowded on the inner tracks than on the outer tracks .
The industry is seeking to incresse data capacity by making the density of transitions more uniform throughout the disk surface.
"Constant density recording comes alive with new chips", Electronic Design, November 13, 1986, p. 141, is evidence of the approach currently being taken. The articLe suggests using a higher clock frequency for outer tracks, hence increasing the number of transitions ~ 31737~
recorded there and the overall disk surface capacity. Because of the higher clock frequency used on outer tracks, more bits are recorded as the disk rotates one revolution.
Varying the frequency in this manner presents some engineering problems in designing the channel to handle a range of frequencies.
Also, synchronous DASD architectures are less amenable to variable bit rates than nonsynchronous architectures. Other attempts include the suggestion of making outer tracks narrower than inner tracks; or ~Tarying the rotational speed of a disk faster as a function of increasing track radii, so that a constant rate of transition can be recorded throughout the disk surface. To those skilled in the art, however, it i6 readily clear that these approaches are inefficient because of the complicated mechanical design and implementation involved.
.
An object of this ilivention is to increase disk storage capacity by exploiting track length differènces between outer tracks and inner tracks. It is another object of this invention that such increase be accomplished with only minimal impact on the design, such as using only a single clock frequency, and manufacturing of the disk device.
This invention accomplishes uniformity of transition density throughout a disk surface by keeping the same clock frequency, but changing the code used. Outer tracks use higher rate codes than inner tracks. That is, the code used on outer tracks requires fewer "0's" between "1's". The use of higher rate codes on the outer tracks tends to equalize the transition densities between the outer and inner tracks. And, because higher rate codes encode more customer bits per transition, the outer tracks contain more customer information than the , . . ~, . . . . .
l3~7~7a inner tracks. The result is an increase in disk surface capacity and a more uniform transition density throughout the surface.
According to this invention, the method in which the above objects are satisfied comprises the steps of: partitioning recording tracks of the device into a plurality of recording bands, including a first band surrounded by an outer band; encoding data being recorded on said first band under a first run-length-limited code; and encoding data being recorded on said outer band under a second run-length-limited code having a higher code rate than said first run-length-limited code.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram of the disk subsystem which embodies the present invention; and Fig. 2 illustrates a disk-` surface partitioned into recording bands according to this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig. 1 illustrates a general implementation of the present invention. In the block diagram of Fig. 1, there is shown a disk storage subsystem which comprises a disk controller 1 for receiving and executing disk read/write commands from a processing unit (not shown), write driver 2 for writing data into the disk stack 3, and detector 4 for reading stored data from the disk stack 3. Details concern;ng the operation of controller 1, the write driver 2 and the ~ 317~7~
detector 4 are all well known in the art and therefore need not be described here.
Included in the disk storage subsystem is a plurality of RLL
encoders 7a,7b, . . ,7n along with their respective counterpart RLL
decoders 9a,9b,.. ,9n. Each encoder has a different code rate, which is commonly understood as the ratio between the number of input data bits to the number of encoded bits produced therefrom (for example, the code rate is 1:2 for the (2,7) code, 2:3 for the (1,7) code, and 8:9 for the (0, 3) code) .
By way of example, the operation of a disk storage subsystem having a (1,7) RLL encoder and a (2,7) RLL encoder is now described.
An example of a (1,7) RLL encoder can be found in U.S. Patent No.
3,689,899 and an example of a (2,7) RLL encoder can be found in U.S.
Patent No. 4,413,251).
As illustrated in Fig. 2, the recording surface of each disk is divided into an inner recording band Bi extending from the track with radius R1 to a track with radius R2, and an outer recording band Bo extending from the track with radius R2 to the track with radius R3.
Data to be recorded on Bi will be encoded under the (2,7) code while data to be recorded on Bo will be encoded under the (1,7) code.
Although the recording surface can be divided in many different ways, it is obvious that the division should be made to maximize the storage capacity of the surface given the set of RLL codes.
Included in each disk read/write command is a track address, from which the controller 1 generates a head position signal S for directing, 131~
via the head servo control 6, the recording/sensing head of the disk stack 3 to a radial position where the corresponding operation of the disk command is to be performed.
In performing a write operation, the data to be stored is received by both the (1,7) and the (2,7) encoders. However, only the output of one encoder is selected by encoder select 8 to be gated to write driver 2 for wrîting into the disk stack 3. This selection is made by comparing the corresponding head position 5 of the operation with the values R1, R2 and R3. As a result, data stored in inner band Bi will be encoded under the (2,7) RLL code while data stored in outer band Bo will be encoded under the (1,7) RLL code, which has a higher code rate than the ( 2,7) code .
Similarly, in performing a read operation, the signal from the detector 4 is received by the (i,7) decoder and the (2,7) decoder.
However, only the output of one of these decoders is selected by decoder select 10 to be gated` to controller 1. The selection is also based upon comparison between the corresponding head position with R1, R2 and R3-It will be understood that if desired, the recording disk may be partitioned into more than two concentric recording bands, with each respective band having a higher run-length-limited code rate than any corresponding adjacent inner band. For example, the recording surface can be partitioned into an innermost first band wherein data is encoded under a (2,7) RLL code, a second band, on the outside of the first band, wherein data is encoded under a (1,7) RLL code, and an outermost is third wherein data is encoded under a (0,3) RLL code.
~317~l~
Also, if desired, other RLL codes, or other combinations of R~L codes may be used. While the codes can be varied, the same clock frequency is always maintained in any given embodiment.
While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in detail may be made therein without departing from the spirit, scope and teaching of the invention.
Claims (11)
1. A method for increasing the effective storage capacity of a disk storage device, comprising the steps of:
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) encoding data being recorded on said first band under a first run-length-limited code; and (c) encoding data being recorded on said second band under a second run-length-limited code having a higher code rate than said first run-length-limited code.
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) encoding data being recorded on said first band under a first run-length-limited code; and (c) encoding data being recorded on said second band under a second run-length-limited code having a higher code rate than said first run-length-limited code.
2. A method according to claim 1 wherein one of said first and second run-length-limited codes is a (1,7) code.
3. A method according to claim 1 wherein one of said first and second run-length-limited codes is a (2,7) code.
4. A method according to claim 1 wherein said first run-length-limited code is a (2,7) code and said second run-length-limited code is a (1,7) code.
5. A method for increasing the effective storage capacity of a disk storage device, comprising the steps of:
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) using a detector operative at one clock frequency and one decoder, decoding data recorded on said first band in a first run-length-limited code;
(c) using the same detector operative at said one frequency and another decoder, decoding data recorded on said second band in a second run-length-limited code having a higher code rate than said first run-length-limited code; and (d) responsive to the track address designated in a disk read command, selectively connecting one of said decoders to the detector for reading data at said frequency on that band which includes said address.
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) using a detector operative at one clock frequency and one decoder, decoding data recorded on said first band in a first run-length-limited code;
(c) using the same detector operative at said one frequency and another decoder, decoding data recorded on said second band in a second run-length-limited code having a higher code rate than said first run-length-limited code; and (d) responsive to the track address designated in a disk read command, selectively connecting one of said decoders to the detector for reading data at said frequency on that band which includes said address.
6. A method for increasing the effective storage capacity of a disk storage device, comprising the steps of:
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) providing a first encoder for encoding data in one run-length-limited code for recording on said first band;
(c) providing another encoder for encoding data for recording on said second band in another run-length-limited code having a higher code rate;
(d) providing a write driver operative at a selected frequency; and (e) responsive to the track address designated in a disk write command, selectively connecting one of said encoders to the write driver for recording data at said frequency on that band which includes said address.
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) providing a first encoder for encoding data in one run-length-limited code for recording on said first band;
(c) providing another encoder for encoding data for recording on said second band in another run-length-limited code having a higher code rate;
(d) providing a write driver operative at a selected frequency; and (e) responsive to the track address designated in a disk write command, selectively connecting one of said encoders to the write driver for recording data at said frequency on that band which includes said address.
7. In a disk storage subsystem, apparatus for increasing the storage capacity of a disk storage device, comprising:
(a) a first encoder receiving a stream of data for encoding it under a first run-length-limited code;
(b) a second encoder receiving a stream of data for encoding it under a second run-length-limited code, said second run-length-limited code having a higher code rate than said first run-length-limited code; and (c) means responsive to a track address designated in a disk command for selectively activating said first and said second encoders.
(a) a first encoder receiving a stream of data for encoding it under a first run-length-limited code;
(b) a second encoder receiving a stream of data for encoding it under a second run-length-limited code, said second run-length-limited code having a higher code rate than said first run-length-limited code; and (c) means responsive to a track address designated in a disk command for selectively activating said first and said second encoders.
8. A method for increasing the effective storage capacity of a disk storage device, comprising the steps of:
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) providing a first encoder for encoding data in one run-length-limited code for recording on said first band;
(c) providing another encoder for encoding data for recording on said second band in another run-length-limited code having a higher code rate;
(d) providing a write driver operative at one clock frequency; and (e) responsive to the track address designated in a disk write command, selectively connecting one of said encoders to the write driver for recording data at said one frequency on that band which includes said address;
(f) using a detector operative at said one clock frequency and one decoder, decoding data recorded in said first band;
(g) using said detector operative at said one clock frequency and another decoder, decoding data recorded in said second band; and (h) responsive to the track address in a disk read command, selectively connecting one of the decoders to the detector for reading data at said one frequency on that band which includes the last mentioned address.
(a) partitioning recording tracks of the device into a plurality of concentric recording bands, including a first band surrounded by an outer second band;
(b) providing a first encoder for encoding data in one run-length-limited code for recording on said first band;
(c) providing another encoder for encoding data for recording on said second band in another run-length-limited code having a higher code rate;
(d) providing a write driver operative at one clock frequency; and (e) responsive to the track address designated in a disk write command, selectively connecting one of said encoders to the write driver for recording data at said one frequency on that band which includes said address;
(f) using a detector operative at said one clock frequency and one decoder, decoding data recorded in said first band;
(g) using said detector operative at said one clock frequency and another decoder, decoding data recorded in said second band; and (h) responsive to the track address in a disk read command, selectively connecting one of the decoders to the detector for reading data at said one frequency on that band which includes the last mentioned address.
9. A method according to claim 8 wherein one of said first and second run-length-limited codes is a (1,7) code.
10. A method according to claim 8 wherein one of said first and second run-length-limited codes is a (2,7) code.
11. A method according to claim 8 wherein said first run-length-limited code is a (2,7) code and said second run-length-limited code is a (1,7) code.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/119,010 US4804959A (en) | 1987-11-10 | 1987-11-10 | Method and apparatus using multiple codes to increase storage capacity |
| US07/119,010 | 1987-11-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1317370C true CA1317370C (en) | 1993-05-04 |
Family
ID=22382096
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000577641A Expired - Fee Related CA1317370C (en) | 1987-11-10 | 1988-09-16 | Method and apparatus using multiple codes to increase storage capacity |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4804959A (en) |
| EP (1) | EP0316084B1 (en) |
| JP (1) | JPH077582B2 (en) |
| CA (1) | CA1317370C (en) |
| DE (1) | DE3886697T2 (en) |
Families Citing this family (27)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5068858A (en) * | 1989-12-21 | 1991-11-26 | International Business Machines Corporation | Error correction capability varied with track location on a magnetic or optical disk |
| WO1991019290A1 (en) * | 1990-05-25 | 1991-12-12 | Hitachi, Ltd. | Optical information recording/reproducing device using pit edge recording system |
| US5099237A (en) * | 1990-07-10 | 1992-03-24 | Research Corporation Technologies, Inc. | Method and apparatus for providing maximum rate modulation or compression encoding and decoding |
| JP2536984B2 (en) * | 1991-09-26 | 1996-09-25 | インターナショナル・ビジネス・マシーンズ・コーポレイション | Peripheral device control method, floppy disk device control method, peripheral device, floppy disk device, and data processing system |
| JP2594202B2 (en) * | 1992-02-25 | 1997-03-26 | 三洋電機株式会社 | Digital signal processor |
| JP2648554B2 (en) * | 1992-08-13 | 1997-09-03 | インターナショナル・ビジネス・マシーンズ・コーポレイション | Asynchronous gain adjustment method and apparatus for PRML disk drive system |
| US5422761A (en) * | 1992-11-20 | 1995-06-06 | International Business Machines Corporation | Disk drive with redundant recording |
| JP3106750B2 (en) * | 1992-12-11 | 2000-11-06 | 松下電器産業株式会社 | Disc playback device |
| US5444719A (en) * | 1993-01-26 | 1995-08-22 | International Business Machines Corporation | Adjustable error-correction composite Reed-Solomon encoder/syndrome generator |
| US5408234A (en) * | 1993-04-30 | 1995-04-18 | Apple Computer, Inc. | Multi-codebook coding process |
| KR0135793B1 (en) * | 1994-11-29 | 1998-05-15 | 김광호 | (4,20) run length limited code producing method and apparatus thereof |
| US5684478A (en) * | 1994-12-06 | 1997-11-04 | Cennoid Technologies, Inc. | Method and apparatus for adaptive data compression |
| KR0182501B1 (en) * | 1996-06-12 | 1999-04-15 | 김광호 | Hard disk drive |
| US6233289B1 (en) * | 1996-07-17 | 2001-05-15 | Seagate Technolgy, Inc. | High rate trellis code for partial response channels |
| US6624761B2 (en) * | 1998-12-11 | 2003-09-23 | Realtime Data, Llc | Content independent data compression method and system |
| US6604158B1 (en) | 1999-03-11 | 2003-08-05 | Realtime Data, Llc | System and methods for accelerated data storage and retrieval |
| US6601104B1 (en) | 1999-03-11 | 2003-07-29 | Realtime Data Llc | System and methods for accelerated data storage and retrieval |
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| US7417568B2 (en) * | 2000-10-03 | 2008-08-26 | Realtime Data Llc | System and method for data feed acceleration and encryption |
| US9143546B2 (en) * | 2000-10-03 | 2015-09-22 | Realtime Data Llc | System and method for data feed acceleration and encryption |
| US8692695B2 (en) | 2000-10-03 | 2014-04-08 | Realtime Data, Llc | Methods for encoding and decoding data |
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| JP3950021B2 (en) * | 2002-07-31 | 2007-07-25 | 株式会社東芝 | Run length limited code generation method, run length limited code recording / reproducing apparatus, and run length limited code recording / reproducing method |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3689899A (en) * | 1971-06-07 | 1972-09-05 | Ibm | Run-length-limited variable-length coding with error propagation limitation |
| US4432025A (en) * | 1981-05-29 | 1984-02-14 | International Business Machines Corporation | System and method for formatting pairs of concentric magnetic tracks of different capacity to a plurality of equal capacity logical tracks |
| US4564869A (en) * | 1983-11-21 | 1986-01-14 | Eastman Kodak Company | Zoned equalization for a magnetic disc |
| US4714967A (en) * | 1985-11-14 | 1987-12-22 | Eastman Kodak Company | Binarily related variable rate recorder |
-
1987
- 1987-11-10 US US07/119,010 patent/US4804959A/en not_active Expired - Fee Related
-
1988
- 1988-08-19 JP JP63204865A patent/JPH077582B2/en not_active Expired - Lifetime
- 1988-09-16 CA CA000577641A patent/CA1317370C/en not_active Expired - Fee Related
- 1988-10-24 DE DE3886697T patent/DE3886697T2/en not_active Expired - Fee Related
- 1988-10-24 EP EP88309966A patent/EP0316084B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH077582B2 (en) | 1995-01-30 |
| EP0316084A3 (en) | 1990-10-10 |
| DE3886697D1 (en) | 1994-02-10 |
| EP0316084A2 (en) | 1989-05-17 |
| JPH01137410A (en) | 1989-05-30 |
| DE3886697T2 (en) | 1994-06-23 |
| EP0316084B1 (en) | 1993-12-29 |
| US4804959A (en) | 1989-02-14 |
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